(1) Field of the Invention
This disclosure pertains to a system or method and apparatus for controlling the injection of propane into a gas or diesel internal combustion engine.
(2) Description of the Prior Art
One attempt to provide a safe and effective propane injection system for an internal combustion engine is the Reggiani, U.S. Pat. No. 4,632,083 (1986) that shows a feedback and monitoring system for controlling the amount of propane injected into an internal combustion engine. Propane flow is determined by controlling pressures of propane to be injected into the fuel-air mixture and comparing intake manifold pressures to determine the flow of propane needed depending on the speed and load to maintain a predetermined fuel air ratio of 1.24. The Reggiani device is primarily concerned with maintaining a constant air-fuel ration during various engine speeds. There are no safety devices such as provided by the device and system disclosed herein and there is no programmable microprocessor to allow each unit to be pre programmed and customized as needed during use.
Other prior art devices used to inject propane into engines are of the type shown in the Fehr, U.S. Pat. No. 4,953,515 (1990) that shows a system for injecting propane into a diesel engine based on the turbo charger boost pressure. In other words, when the engine turbo-charger is activated to increase air flow to the engine, resultant pressure increase occurs in the intake manifold of the engine. A series of pressure sensors are coupled to the turbo-charger to monitor this boost pressure and are coupled to propane injectors that feed propane in steps to the primary air fuel mix as the boost pressure rises thereby admitting progressively increasing amounts of the secondary fued, propane, to the engine. While the structure and operation of the Fehr arrangement does monitor boost pressure to vary the amount of secondary fuel, each one of the monitoring or pressure switches must be individually set at a specific pressure level to open a propane injecting valve. There are no safety monitoring devices or shut offs to prevent damage to the engine as provided by the devices and system disclosed herein.
Another example of a propane injection system is shown in the Long, U.S. Pat. No. 6,422,015 (2002) that shows an attempt to overcome the drawbacks of the Fehr patent disclosure discussed above. Namely, Long shows a system that replaces the individual pressure sensing switches of Fehr with a diaphragm regulator valve that provides constant regulation of flow of the secondary fuel or propane rather than stepped flow shown in the Fehr patent. The Long patent also shows an on-off propane valve that is controlled with an electric switch to turn the system on and off from inside the vehicle. While this arrangement is different, it does not provide for adjustment or the safety features of this invention that includes an exhaust manifold temperature sensing probe to shut off the propane if engine temperatures rise to predetermined level. Further, this disclosure shows and driver accessible on off switch with a warning light for manual override if engine temperatures rise too high.